Removal of Interfering Substances

Overview

Success or failure of any protein analysis depends on sample purity. Interfering substances that can negatively impact gel electrophoresis include salts, detergents, denaturants, or organic solvents (Evans et al. 2009). Bio-Rad products that can be used for contaminant removal are discussed in this section.

Page Contents

Interfering Substances

In addition to chemical contaminants, protein samples may contain an excess of biomolecules such as DNA or carbohydrates. Highly viscous samples indicate high DNA and/or carbohydrate content, which may also interfere with PAGE separations. In addition, solutions at extreme pH values, such as fractions from ion exchange chromatography, diminish the separation power of most electrophoresis techniques. Use one of the following methods as needed to remove these contaminants:

Protein precipitation — the most versatile method to selectively separate proteins from other contaminants consists of protein precipitation by trichloroacetic acid (TCA)/acetone followed by resolubilization in an electrophoresis sample buffer. A variety of commercial kits can simplify and standardize laboratory procedures for protein isolation from biological samples

Buffer exchange — size exclusion chromatography is another effective and rapid method for removing salts, detergents, and other contaminants

Products for Contaminant Removal

Bio-Rad offers kits designed for removal of salts, detergents, and other contaminants. They incorporate procedures such as precipitation and size exclusion chromatography to improve resolution of SDS-PAGE and 2-D gels. For contaminant removal Bio-Rad offers the following:

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